Add test for interface code generation

tests/code_generation/CodeGeneration.sol

@@ -0,0 +1,56 @@
+pragma solidity ^0.8.4;
+interface I {
+  enum SomeEnum { ONE, TWO, THREE }
+  error ErrorWithEnum(SomeEnum e);
+}
+
+contract TestContract is I {
+    uint public stateA;
+    uint private stateB;
+    address public immutable owner = msg.sender;
+    mapping(address => mapping(uint => St)) public structs;
+
+    event NoParams();
+    event Anonymous() anonymous;
+    event OneParam(address addr);
+    event OneParamIndexed(address indexed addr);
+
+    error ErrorSimple();
+    error ErrorWithArgs(uint, uint);
+    error ErrorWithStruct(St s);
+
+    struct St{
+        uint v;
+    }
+
+    function err0() public {
+        revert ErrorSimple();
+    }
+    function err1() public {
+        St memory s;
+        revert ErrorWithStruct(s);
+    }
+    function err2(uint a, uint b) public {
+        revert ErrorWithArgs(a, b);
+        revert ErrorWithArgs(uint(SomeEnum.ONE), uint(SomeEnum.ONE));
+    }
+    function err3() internal {
+        revert('test');
+    }
+    function err4() private {
+        revert ErrorWithEnum(SomeEnum.ONE);
+    }
+
+    function newSt(uint x) public returns (St memory) {
+        St memory st;
+        st.v = x;
+        structs[msg.sender][x] = st;
+        return st;
+    }
+    function getSt(uint x) public view returns (St memory) {
+        return structs[msg.sender][x];
+    }
+    function removeSt(St memory st) public {
+        delete structs[msg.sender][st.v];
+    }
+}

tests/test_code_generation.py

@@ -0,0 +1,25 @@
+import os
+
+from solc_select import solc_select
+
+from slither import Slither
+from slither.core.expressions import Literal
+from slither.utils.code_generation import (
+    generate_interface,
+    generate_interface_function_signature,
+    generate_struct_interface_str,
+)
+
+SLITHER_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+CODE_TEST_ROOT = os.path.join(SLITHER_ROOT, "tests", "code_generation")
+
+
+def test_interface_generation() -> None:
+    solc_select.switch_global_version("0.8.4", always_install=True)
+
+    sl = Slither(os.path.join(CODE_TEST_ROOT, "CodeGeneration.sol"))
+
+    with open("actual_generated_code.sol", "w", encoding="utf-8") as file:
+        file.write(generate_interface(sl.get_contract_from_name("TestContract")[0]))
+
+